Current Issue : July-September Volume : 2022 Issue Number : 3 Articles : 5 Articles
This paper presents the evaluation of the potential aggregate source for pavement construction in Pakistan. Recently the demand for construction materials has been increased significantly due to the establishment of the China- Pakistan Economic Corridor (CPEC) Projects. Therefore, it is essential to look for new resources of construction materials along with the CPEC routes in consideration of this increasing demand. In this context, a Physical and Mechanical characterization investigation is carried out on the Permian Wargal Limestone from Zaluch Nala, Salt Range to explore their potential to utilize as construction materials. The studied samples have tolerable values for all standard engineering parameters, proposed by various national and international agencies such as AASHTO, ASTM, BS, and NHA. Furthermore, as a performance indicator of aggregate overall quality, the evaluated mechanical qualities were integrated into a single characteristic, Toughness Index (TI). The TI values also suggested that the Permian Wargal limestone aggregates meet international quality standards for pavement construction. On the basis of geotechnical testing and Toughness Index (TI), the late Permian Wargal limestone, Zaluch Nala, Salt Range, is strongly recommended as a potential aggregate resource for mega projects such as the China-Pakistan Economic Corridor (CPEC) and other construction projects....
Recent research showed that ultrahigh-performance concrete (UHPC) and orthotropic steel bridge decks could be integrated to form steel-UHPC composite sections offering superior load-carrying capacity and fatigue resistance. This study investigates the effects of longitudinal stiffener types on the fatigue resistance of steel-UHPC composite sections. Three types of longitudinal stiffeners were compared, including U-ribs, bulb flat ribs, and plate ribs. Finite element analysis and full-scale fatigue tests were performed to investigate the load-carrying capacity and fatigue resistance of the composite bridge decks with different stiffeners. Besides, the proposed steel-UHPC composite bridge decks were compared with conventional orthotropic steel decks. The results show that steel box girders with bulb flat rib composite deck have reasonable fatigue resistance, construction efficiency, and economic benefits. This study is expected to promote the design and evaluation of economic steel-UHPC composite bridge decks to achieve higher mechanical performance and long-term durability....
In response to a series of national strategic guidelines for green and sustainable development, recycled concrete is used as a recyclable resource. First, the mechanical properties, workability, and durability of recycled concrete are briefly introduced, and the benefit and necessities of research on recycled concrete are described from environmental, economic, and social perspectives. Second, the mixing method and molding process of recycled concrete are described in detail, and the influence of vibration molding and compression molding on the performance of recycled concrete is analyzed. It is found that the compressive strength first increases and then decreases with the increase ofmolding pressure. In addition, porosity decreases asmolding pressure buildup. Therefore, it is recommended that the molding pressure of recycled concrete be generally controlled between 600 and 800 N. Then, the influence of the water-cement ratio on recycled concrete’s fluidity and mechanical properties is discussed. It is found that with the increase of the water-cement ratio, the compressive strength first increases and then decreases and the optimum water-cement ratio is proposed to be 0.2. Finally, the application status and problems of recycled concrete in road engineering are briefly described, and relevant suggestions for construction technology are put forward. Based on the fire safety and reliability requirements of concrete structures, the performance of high-performance concrete structures after fire can be restored to the initial level or even improved through the processes and measures of building structure design, repair, and reinforcement; the strength and crack healing of high-performance concrete after fire can be gradually restored by applying or soaking repair agent and water curing; the recovery of pH value of concrete after fire and the reduction of carbonation depth can be realized by using electrochemical realkalization technology; using carbon fiber to strengthen the components after fire can restore the bearing capacity, but the degree of stiffness recovery is low; and beam side steel plate reinforcement and steel bonding reinforcement can realize the recoverability of bearing capacity, stiffness, and ductility of members after fire....
The use of plastic has grown extensively in recent years all over the world. It is inexpensive and easily available and can bemoulded into any shape. However, plastic is nonbiodegradable; it causes pollution and create difficulties in managing even for a wealthy nation. The purpose of this study was to investigate the environment-friendly potential use of plastic and demonstrate usefulness of plastic sand bricks as alternative structural elements, replacing standard clay brick. The physical and mechanical properties of plastic sand bricks were studied in different plastic sand ratios of 1 : 3, 1 : 4, and 1 : 5 by their weight, using plastic as a binder. Moreover, the thermal resistance test, split tensile strength test, penetration test, and Fourier transform infrared spectroscopy were performed. The study concluded that the strength of plastic sand brick depends upon the uniformity of the mixture and increases when the ratio of sand and plastic in themixture is increased to 1 : 4 from1: 3. Any increase or decrease in the ratio 1 : 4 is found to reduce the strength. All the bricks in any of the ratios showed zero water absorption and nil efflorescence....
This study explored the seismic response of a house supporting base sides with a polymeric displacement control material and by magnetically levitating the foundation base. In this paper, we explore the possibility and efficacy of a seismic-isolated detached house as described above from both a shaking table experiment of model and three-dimensional finite element analysis. The seismic-isolated model showed stable response and its acceleration response was significantly reduced compared to the base-fixed model in the shaking table test. Three-dimensional finite element analysis was possible to simulate the experimental results. In the seismic response analysis of a full-scale detached house, the seismic-isolated model showed response reduction and its residual displacement was smaller than that of the sliding-base isolation model....
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